DE691366C - Process for the production of potash salts from solutions - Google Patents

Description

Process for obtaining potash salts from solutions It is known (see, for example, Mikro-Chemie 1934, p. 265, Angewandte Chemie, 1936, S- 827 and reports of the German Chemical Society for February 1938 '- p. 220) that Hexanitrodiphenylamine (dipikrylamine) with potassium, rubidium and cesiuril forms salts that are very sparingly soluble in water, while other salts of this organic acid, e.g. B. their sodium, lithium, magnesium and calendum salts, easily water: are soluble.

It has also been suggested in the literature references cited above to use this behavior in analytical chemistry for the quantitative determination of potassium in such a way that the solution to be investigated is treated with an excess of about 25111 magnesium dipicrylamine and the resulting precipitate is immediately filtered off, then washed out, dried and finally used for calibrating. After the potassium content has been determined, the precipitated salt is processed again on the reagent in such a way that the precipitate is dissolved in acetone, the resulting solution is decomposed with dilute sulfuric acid and the dipicrylamine which precipitates is converted again into a salt solution that can be used for precipitation.

This analytical method comes for a technical extraction of Potash salts not taken into consideration, because on the one hand there are very considerable proportions of them of the precipitant introduced into the process are lost and on the other hand the acetone required to dissolve the resulting precipitate is an expensive one Requires recovery from the dilute aqueous saline solution and also that finally obtained potassium sulfate in such a dilute solution that the Concentration of such solutions would cause economic difficulties.

In contrast, it has now surprisingly been found that it does not dissolve the resulting potassium dipicrylamine precipitate with acetone is required if this precipitate is mixed with nitric acid and similar acids treated, since he deals with such as opposed to dilute sulfuric acid converts easily with release of dipikrylamine, through which one to a very simple and economical, even on an industrial scale feasible method arrives in the context of which the implementation mentioned released dipikrylamine then nitrate formed in the usual way by Ader. O. Like. Solution separated and then used again in the process. A Another advantage of such an approach is that it in no way requires the use of a large excess of precipitant. On the contrary, it is preferable to use the precipitant without a substantial excess, preferably to use approximately equivalent amounts in the potash content of the salt solution. The precipitation of the potassium content does not take place completely, however, as it is based on the analytical method mentioned at the beginning. But this is irrelevant in the context of the present proceedings, because in the same not only the dipikrylamine recovered from the potassium precipitation, but together with it also the unreacted dipicrylamine remaining in the solution or transferred into the filtrate after it has been precipitated by the addition of acid in the circuit for the treatment of others Potassium-containing starting solutions are used again and again. In this way it is thus possible to use potassium nitrate and the like potassium salts without any significant consumption of dipikrylamine and thus in a very economical way on an industrial scale from sea water, salt lakes, salt pans, mother liquors and other aqueous solutions to win, which contain only small amounts of potash.

The possibility of practicing this process depends, inter alia, on the fact, which has been established by experiments, that the water-insoluble potassium dipicrylamine in the presence of nitric acid or a similar acid reacts directly with this acid, i. H. without being dissolved beforehand, the reaction is carried out in such a way that potassium is bound to acid and dissolves, while insoluble dipikrylamine remains in the form of practically unchanged crystals.

The present method can be used for a number of different Brine solutions, which contain potash, are used as the starting material but is particularly beneficial for the treatment of seawater, namely, because all metals, apart from potassium, whose salts are dissolved in seawater, form easily soluble compounds with dipikrylamine.

In order to obtain potash salts from salt solutions according to the invention, the salt solution is a solution of a readily soluble dipicrylamine salt, preferably Calcium dipicryl laminate, added, causing the potassium dipicryl laminate to precipitate and separates out as a .effte crystalline mass, which passes through the solution Filtration, decantation or otherwise can be separated.

With regard to the amount of dipicrylamine used, it has become how Already mentioned above, proven to be advantageous, without a substantial excess, or possibly even with a little deficiency of dipikrylamine, based on the total Potash content of the solution to be treated, e.g. B. sea water to work.

The reaction of the precipitated potassium dipikrylaminate by means of acid is expediently carried out at ordinary temperature, e.g. B. 2o 'made. It is also advisable to work with a 5 to: 2o0 /, strength, preferably about 14% acid.

After the precipitated crystalline mass has been separated off, the Solution made acidic by the addition of an acid, whereby the remained in solution or unreacted portion of the precipitant, e.g. B. calcium dipicryl laminate, cleaved and insoluble dipikrylamine is excreted, which is filtered through can be recovered.

For the precipitation of the Dipikrylainins any acid can be used for this purpose is suitably a readily used for loading creating cheap mineral acid. It is also advisable to use an acid addition such that the filtrate has a pn value of less than 5, preferably 3.5 to 4.0.

After filtering, the solution contains only traces of Dipikryla-min.

The filtered potassium dipikrylaminat is, as indicated above, through Nitric acid or a similar acid decomposes, producing potassium nitrate or the other potassium salt in question is formed while free dipicrylamine is excreted will.

The solution is filtered and prepared for potash salts in a known manner, while the dipikrylamine excreted in the two acid treatments mentioned by means of milk of lime in calcium dipikrylaniinat is converted, which again for new precipitation of potassium dipicryl laminate from the potassium-containing salt solution to be treated is used.

In a corresponding experiment it has been found that in this way z. B. can gain more than 8o0 /, & s of potassium contained in seawater. The following examples show how the process can be carried out, if one wants to produce potassium nitrate: Example I To ioo 1 ocean water with a content of about 73 9 K Cl were stirring at 16 to 18 '420g hexanitrodiphenylamine (HiN (C, H, (N 0,),),) was added, which was dissolved in 8 l of milk of lime, which had a content of 279 Ca0 and was filtered before the addition. A red crystal mass was precipitated, which was filtered off after 15 minutes and washed with water. The filter cake W09 4359, 70 % of which were potassium dipicryl laminate (KN (C.H2 (iN02) 3) 2). The rest was water.

This filter cake was then treated at 2o0 with 270 ml of 14% nitric acid while stirring for '/ 4 hours, the crystal mass becoming orange-yellow by being converted into dipikrylamine with conversion with nitric acid without any detectable change in the crystal structure, during the Potash content of the crystals as nitrate went into solution. Finally the mass was filtered off and washed.

The amount of potassium nitrate in the solution (the filtrate) corresponded to a conversion of 93 % of the nitric acid used.

The first filtrate from io8 1 having a content of unreacted Caliciumdipikrylaminat was added that a pl was achieved of 3.6 as much 470 /, nitric acid. This caused the dipicrylamine to precipitate. Example II To ioo 1 ocean water with a content of about 73 9 KC1 were stirring at io to -1: 2 '39o g hexanitrodiphenylamine zuigesetzt which in: filtered having 25 g of Ca0 and before the addition of 21 milk of lime having a content of was, was dissolved. The filter cake w09 480 9 and was treated at 5 " with 345 ml 14% nitric acid and further as under I.

Yield roughly as with I.

Results #which correspond to those of the above example were obtained achieved with other potassium-containing salt solutions, e.g. 13. With a saline solution that coincides with the composition of the water in the Dead Sea.

In the accompanying drawing are the course of the invention Method (Fig. I) and that of the analytical method mentioned at the beginning (Fig. 2) shown schematically and at the same time the fundamental differences to be seen between the two.

Claims (2)

PATENT FRUITS: i. The method includes for the recovery of potash from sea water, salt lakes, Salinen, mother liquors and other wäßrigerl solutions which only relatively u nts Kali, characterized slight Me, that the potash from the solutions initially known for analytical purposes in itself method of payment by the addition of a soluble dipicrylamine salt, preferably calcium dipicrylamine, is precipitated as Y,., aliumdipiklylanünat, the latter is then removed and mixed with nitric acid or a similar acid and thus on the one hand a solution of the corresponding potassium salt and on the other hand insoluble dipikrylamine is obtained, whereupon the former is further processed according to known methods .-processed and the latter together with dipicrylamine precipitated from the filtrate from the potassium dipicrylamine precipitation by the addition of acid, after conversion into a soluble dipicrylamine salt (e.g. calcium dipicrylamine) in the circuit for the treatment of further potassium-containing starting solutions again and again v is used. . 2. The method according to claim i, characterized in that the precipitating agent is used without a substantial excess, preferably in amounts approximately equivalent to the potassium content of the salt solution. 3. The method according to claim i or 2, characterized in that the reaction of the precipitated potassium dipikrylaminats, by means of acid at ordinary temperature, for. B. 2o ". 4. Process according to one of the preceding claims, characterized in that the reaction of the precipitated potassium dipikrylaminate is carried out by means of acid with an approximately 5 to 20% acid. 5. Process according to one of the The preceding claims, characterized in that the decomposition of the unreacted dipicrylamine salt in the resulting filtrate is carried out with an addition of acid such that it has a pH value less than about 5, preferably 3.5 to 4.